For the purpose of improving light-reflecting efficiency of photographic printing paper as well as water-resisting property thereof, a resinous coating containing titanium oxide kneaded with and thereby dispersed in a polyolefin, such as polyethylene or the like, has so far been provided on the front side of a raw paper (to which emulsions are to be applied). While the titanium oxide therein can enhance the image quality, particularly through its heightening the whiteness of photographic printing paper, it adversely affect the surface smoothness of printing paper.
Such polyolefins as described above have been widely used as resins having excellent workability because of their high flexibility.
However, polyelefin resins, though excellent in flexibility, are low in stiffness. That is, they are inferior in self-supportability and lacks in a rigid feeling.
Thus, there have been proposed the photographic printing paper supports having polyethylene terephthalate coatings on both sides thereof [JP-A-56-870388 (the term "JP-A" as used herein means an "unexamined published Japanese patent application"), JP-A-60-238828, JP-A-62-31244 and JP-A-62-44734]. These supports however have a defect such that only the coating provided on the back side of a raw paper deteriorates its adhesiveness to the raw paper with the lapse of time, and a reason why this phenomenon occurs is not yet explained.
As a result of our intensive study for obviating the above-described defect, it has been found out that the adhesion between a raw paper and a coating provided on the back side thereof did not change with lapse of time when the coating was constituted of polyethylene terephthalate or a resin blend of polyethyleneterephthalate and another resin (which is abbreviated as "a resin blend" hereinafter) and inorganic grains having their sizes in a specified range, thereby achieving the present invention.